Local application of zoledronate inhibits early bone resorption and promotes bone formation

Ming-Kai Hsieh; Chi-Yun Wang; Fu-Cheng Kao; Hui-Ting Su; Mei-Feng Chen; Tsung-Ting Tsai; Po-Liang Lai

doi:10.1093/jbmrpl/ziae031

Local application of zoledronate inhibits early bone resorption and promotes bone formation

JBMR Plus. 2024 Mar 9;8(5):ziae031. doi: 10.1093/jbmrpl/ziae031. eCollection 2024 May.

Authors

Ming-Kai Hsieh^{1

2}, Chi-Yun Wang^{2

3}, Fu-Cheng Kao^{1

2}, Hui-Ting Su^{1

2}, Mei-Feng Chen^{1

2}, Tsung-Ting Tsai^{1

2}, Po-Liang Lai^{1

2}

Affiliations

¹ Department of Orthopaedic Surgery, Spine Section, Chang Gung Memorial Hospital, Linkou, Taiwan and College of Medicine, Chang Gung University, Taoyuan 33305, Taiwan.
² Bone and Joint Research Center, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan.
³ International Ph.D. Program in Innovative Technology of Biomedical Engineering and Medical Devices, Ming Chi University of Technology, Taishan Dist, New Taipei City 243303, Taiwan.

Abstract

Nonunion resulting from early bone resorption is common after bone transplantation surgery. In these patients, instability or osteoporosis causes hyperactive catabolism relative to anabolism, leading to graft resorption instead of fusion. Systemic zoledronate administration inhibits osteoclastogenesis and is widely used to prevent osteoporosis; however, evidence on local zoledronate application is controversial due to osteoblast cytotoxicity, uncontrolled dosing regimens, and local release methods. We investigated the effects of zolendronate on osteoclastogenesis and osteogenesis and explored the corresponding signaling pathways. In vitro cytotoxicity and differentiation of MC3T3E1 cells, rat bone marrow stromal cells (BMSCs) and preosteoclasts (RAW264.7 cells) were evaluated with different zolendronate concentrations. In vivo bone regeneration ability was tested by transplanting different concentrations of zolendronate with β-tricalcium phosphate (TCP) bone substitute into rat femoral critical-sized bone defects. In vitro, zolendronate concentrations below 2.5 × 10^-7 M did not compromise viability in the three cell lines and did not promote osteogenic differentiation in MC3T3E1 cells and BMSCs. In RAW264.7 cells, zoledronate inhibited extracellular regulated protein kinases and c-Jun n-terminal kinase signaling, downregulating c-Fos and NFATc1 expression, with reduced expression of fusion-related dendritic cell‑specific transmembrane protein and osteoclast-specific Ctsk and tartrate-resistant acid phosphatase (. In vivo, histological staining revealed increased osteoid formation and neovascularization and reduced fibrotic tissue with 500 μM and 2000 μM zolendronate. More osteoclasts were found in the normal saline group after 6 weeks, and sequential osteoclast formation occurred after zoledronate treatment, indicating inhibition of bone resorption during early callus formation without inhibition of late-stage bone remodeling. In vivo, soaking β-TCP artificial bone with 500 μM or 2000 μM zoledronate is a promising approach for bone regeneration, with potential applications in bone transplantation.

Keywords: bisphosphonate; drug targeting; mesenchymal stem cells; osteoclast; pathway; rat femoral bone defect.